1. Chairman, Department of Anesthesia, Intensive Care and Pain Therapy, National Institute of Cancer. Professor of Anesthesiology, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
2. Assistant Professor, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
3. Medical Director, Pain Treatment Center. Associate Professor of Anesthesiology and Psychiatry, University of Rochester School of Medicine and Dentistry, Rochester, New York.